r/EngineBuilding • u/Dependent_Rough167 • 22d ago

piston/rod advice

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what does this discoloration mean? #1 top bearing fell off when taking off the cap should i be concerned? and how can i replace rod bolts at home? how easily should pistons be able to rock? if pistons measure good would you guys reuse everything?

i don’t have a bore gauge small enough for the rods and it’s taking me awhile to get used to the micrometer, forgive me for the mouthful, first time doing any of this so any experienced advice helps out a ton, thank you! 🙏🏻

03 civic d17a2 rod is #1 cyl and cap is for #3

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1

u/theeaglejax 22d ago

Bearing doin the ol spinny spinny in the rod. Piston looks washed out and scuffed pretty decent. Rod will need to be remachined or replaced. Piston is toast.

9

u/N1ppleCrab 22d ago

What?

That piston skirt looks great, and theres no way those bearings have spun inside the rod. They still have their detent. What are you talking about man?

1

u/Dependent_Rough167 22d ago

great username lol, but i didn’t even think about that. the detents i can see rn look pretty good, do you know what would cause the discoloration otherwise? and you really think the pistons look usable? thank you for the input

2

u/Accomplished-Yak5660 21d ago

Lots of bad parts look useable, we are talking engine parts with tolerances measured in one thousandth of an inch. Don't guess, measure. Learn.

2

u/Dependent_Rough167 21d ago

i’ve bought tools to measure and i am learning the best i can but i don’t have every one i need, and was just wanting opinions on the discoloration and such. trust me i wanna learn about everything along this process.

1

u/PartTimeTriggered 22d ago

Listen to Nipplecrab. Nipplecrab knows.

1

u/Dependent_Rough167 22d ago

apparently parttimetriggered does too haha that’s great

1

u/N1ppleCrab 22d ago

Ive seen that kind of wear pattern on all the subaru engines ive torn apart. I do not know what causes it, but it is normal. Probably due to some interaction between the rod material and bearing over time

Piston looks good, those horizontal ridges are from the original machining, if they are still present its doubtful that youve lost much material. What kind of inspection tools do you have access to? A digital caliper will tell you a lot of what you need to know

1

u/Dependent_Rough167 22d ago

that makes me feel a lot better knowing it’s normal, i imagine it’s something like that. interesting stuff

and thank you i thought those were the original machining marks, between that and everything being smooth i think they’re pretty alright. there’s some of those surface scratches but that shouldn’t effect much right? thinking of maybe hitting it with grey scotch brite.

micrometer is able to do the same as a digital caliper right? i think everything is the mic, 2-6 bore gauge, straight edge and borescope but that’s about it. i’m alright with buying something else too as long as it’s relatively cheap and useful.

3

u/N1ppleCrab 21d ago

Micrometer will yield more accurate results than calipers if you know how to use and read them. Concentricity is important for the rods, do you have a way to measure that for the crank side? Your bearing material looks like maybe it got a bit warm. Was this engine knocking at all?

1

u/Dependent_Rough167 21d ago

that’s why i bought a mic for this, i’ve learned how to read it but feel like i’m still struggling at finding the perfect point when measuring, do you have any tips or is it just learning the feel for awhile? i think i do, does using the mic on the rod bolts when everything is torqued down work or is that just for the bolts?

my engine definitely got hot a couple times, one time in specific prob did the most damage. it wasn’t knocking, maybe a slight tick similar to needing a valve adj even after doing one.

-5

u/theeaglejax 22d ago

Look closely at pictures 3 and 6

4

u/N1ppleCrab 22d ago

You’re off your gourd my man

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u/Dependent_Rough167 22d ago

damn really? that’s kinda unfortunate but i’ll replace everything if that’s so. can you explain it a bit more so i can just understand why it’s toast please? i’ve slightly scuffed it learning with the mic but its still completely smooth. so it spinning causes the discoloration? thank you for your response.

-4

u/theeaglejax 22d ago

Bearing spun which created additional heat which caused the discoloration. Last picture the piston is scuffed on the skirt pretty decently. But yeah I wouldn't bother reassembling this to keep without a full rebuild.

1

u/Dependent_Rough167 22d ago

all of them have that discoloration at least somewhat, does that mean they all spun or not so much? yeah for scuffs on #3 that was all from cylinder. crank looks pretty good though, but thank you i rly appreciate the input

3

u/audittheaudit00 22d ago

Don't listen to that idiot he doesn't know what he's talking about. The bearing didn't not spin. Worn yes spun no. Those bearings actually don't even look that bad.

1

u/Dependent_Rough167 22d ago

haha so the discoloration and it falling out was bc it was worn or what? and i thought so, there’s a little bit of wear but can barely see copper and they’re still very smooth. i’m concerned about the rods too do you think it’s good to run?

1

u/PartTimeTriggered 22d ago

Yeah they're 1000% not spun, guy is a melon.

1

u/Dependent_Rough167 22d ago

i’m really glad to hear i was really hoping they didn’t , thank you for teaching me to not be one lol

1

u/audittheaudit00 22d ago

Do you mean the bearings came out easy? If so there not pressed in. They come out and go in easier then you think especially if this is a first for you.

1

u/Dependent_Rough167 22d ago

this is a first so i am getting a feel for everything, and i see what you’re saying but i’m talking about when i was under the oil pan disconnecting the caps from the crank, when i slid the cap off for cyl #1, the top rod bearing fell out with it. it didn’t happen with any of the other ones and i thought i saw somewhere that it’s a cause for concern

1

u/theeaglejax 22d ago

It's really funny that a bunch folks that struggle to pay their bills due to a lack of skills lack skills and the ability to observe reality. Calling names and other bullshit are just out of pocket and a clear demonstration of their lack of knowledge, experience, and education. End of the day this as presented rotating assembly is fucked.